"Our estimate of $61.2 billion per year in pain-related lost productive time does not include costs from4 other causes. First, we did not include lost productive time costs associated with dental pain, cancer pain, gastrointestinal pain, neuropathy, or pain associated with menstruation. Second, we do not account for pain-induced disability that leads to continuous absence of 1 week or more. Third, we did not consider secondary costs from other factors such as the hiring and training of replacement workers or the institutional effect among coworkers. Taking these other factors into consideration could increase, decrease, or have no net effect on health-related lost productive time cost estimates. Fourth, we may be prone to underestimating current lost productive time among those with persistent pain problems (eg, chronic daily headache). To the extent that these workers remain employed,they may adjust both their performance and perception of their performance over time. The latter, a form of perceptual accommodation, makes it difficult to accurately ascertain the impact of a chronic pain condition on work in the recent past through self-report."

Source

Stewart, Walter F., PhD, MPH, Judith A. Ricci, ScD, MS, Elsbeth Chee, ScD, David Morganstein, MS, Richard Lipton, MD, "Lost Productive Time and Cost Due to Common Pain Conditions in the US Workforce," Journal of the American Medical Association (Chicago, IL: American Medical Association, Nov. 12, 2003), Vol. 290, No. 18, p. 2452.
http://jama.jamanetwork.com/a…